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==== Optimal viewing distance ====
==== Optimal viewing distance ====
The optimal viewing distance<ref name=":0">{{Cite web |year=2019 |title=Recommandation ITU-R BT.500-14, Methodologies for the subjective assessment of the quality of television images |url=https://www.itu.int/rec/R-REC-BT.500/en |url-status= |access-date=2024-04-11 |website=www.itu.int}}</ref> is based on the limits of the human eye, i.e. its [[Angular resolution|angle of resolution]]. Here, it concerns its ability to distinguish two pixels. For normal [[Visual acuity#Physiology|visual acuity]] (6/6 vision), this angle is 1 [[Minute and second of arc|arcmin]]. To obtain a fixed distance for a given [[Display resolution|resolution]], it must be expressed in picture heights (H)<ref name=":0" />. If a screen is 50 cm high and it is at a distance of 250 cm, then in picture heights, its distance is 5&nbsp;H ({{Sfrac|250|50}}). Mathematically, this results in the distances presented in the following table:
"''The optimal viewing distance''"<ref name=":0">{{Cite web |year=2019 |title=Recommandation ITU-R BT.500-14, Methodologies for the subjective assessment of the quality of television images |url=https://www.itu.int/rec/R-REC-BT.500/en |url-status= |access-date=2024-04-11 |website=www.itu.int}}</ref> is based on the limits of the human eye, i.e. This is  its [[Angular resolution|angle of resolution]]. Here, it concerns its ability to distinguish two pixels. For normal [[Visual acuity#Physiology|visual acuity]] (6/6 vision), this angle is 1 [[Minute and second of arc|arcmin]]. To obtain a fixed distance for a given [[Display resolution|resolution]], it must be expressed in picture heights (H)<ref name=":0" />. If a screen is 50 cm high and it is at a distance of 250 cm, then in picture heights, its distance is 5&nbsp;H ({{Sfrac|250|50}}). Mathematically, this gives the distances shown in the following table:
[[File:Distance in picture heights (H).jpg|alt=A person on a couch watches the TV. Lines show that the distance between the couch and the TV corresponds to 3.2 times the picture heights.|thumb|Distance in picture heights. Here the distance is 3.2 picture heights (H). This is the optimal viewing distance for 1080 HD video.|335x335px]]
[[File:Distance in picture heights (H).jpg|alt=A person on a couch watches the TV. Lines show that the distance between the couch and the TV corresponds to 3.2 times the picture heights.|thumb|Distance in picture heights. Here the distance is 3.2 picture heights (H). This is the optimal viewing distance for [[1080p|HD 1080]] video.|335x335px]]
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This table can be used in various ways :
This table can be used in a number of ways :


'''Find the optimal distance for a given screen'''. Example: for a [[4K resolution#SMPTE UHDTV standard|4K UHD]] 140 cm high (112 inches diagonal) screen, the optimal distance is 140 × 1.6 = 224 cm.
'''Find the optimal distance for a given screen'''. Example: for a [[4K resolution#SMPTE UHDTV standard|4K UHD]] screen 140 cm high (112 inches diagonal), the optimal distance is 140 × 1.6 = 224 cm.


'''Find the right screen size'''. Example: for an [[1080p|HD 1080]] television used at a distance of 250 cm, you need to find a screen whose height is close to {{Sfrac|250|3.2}} = 78 cm (63 inches diagonally).
'''Find the right screen size'''. Example: for a 1080 HDTV used at a distance of 250 cm, you need to find a screen whose height is close to {{Sfrac|250|3.2}} = 78 cm (63 inches diagonally).


'''Find the correct video resolution'''. Example: a screen, whose height is 53 cm (43 inches diagonal), which is at a distance of 300 cm, does not need to present video higher than [[720p|HD 720]]. Presenting greater [[Display resolution|resolution]] results in a greater [[ecological footprint]] without any perceptible gain.
'''Find the right video resolution'''. Example: a 53 cm high screen (43 inches diagonal), located at a distance of 300 cm, does not need to show video with a resolution higher than [[720p|HD 720]]. Presenting a higher [[Display resolution|resolution]] means a larger [[ecological footprint]] with no perceptible gain.


'''Find the best seat at the cinema.''' [[4K resolution#DCI Digital Cinema System Specification|DCI 4K]] cinema has the same number of lines as [[4K resolution#SMPTE UHDTV standard|4K UHD]] ([[4K resolution#DCI Digital Cinema System Specification|DCI 4K]] format is wider). The optimal distance is therefore 1.6 times the height of the screen. The best compromise with the ideal listening zone, the [[Sweet spot (acoustics)|sweet spot]], must be found; "''Sound is 50 percent of the movie going experience"'' - George Lucas<ref>{{Cite news |last=Fantel |first=Hans |date=May 3, 1992 |title=Home Entertainment; In the Action With 'Star Wars' Sound |url=https://www.nytimes.com/1992/05/03/arts/home-entertainment-in-the-action-with-star-wars-sound.html |work=The New York Times}}</ref>.
'''Find the best seat in the cinema.''' [[4K resolution#DCI Digital Cinema System Specification|DCI 4K]] cinema has the same number of lines as [[4K resolution#SMPTE UHDTV standard|4K UHD]] (the [[4K resolution#DCI Digital Cinema System Specification|DCI 4K]] format is wider). The optimal distance is therefore 1.6 times the height of the screen. The best compromise with the ideal listening zone, the [[Sweet spot (acoustics)|sweet spot]], must be found; "''Sound is 50 percent of the movie going experience"'' - George Lucas<ref>{{Cite news |last=Fantel |first=Hans |date=May 3, 1992 |title=Home Entertainment; In the Action With 'Star Wars' Sound |url=https://www.nytimes.com/1992/05/03/arts/home-entertainment-in-the-action-with-star-wars-sound.html |work=The New York Times}}</ref>.


'''Attention !''' The optimal viewing distance is not suitable for [[user interface design]]; It is the distance of use actually observed in households which must be used. It is much larger and highly variable<ref>{{Cite journal |last=Bertolus |first=Cédric |last2=Bailleul |first2=Daniel |last3=Mersiol |first3=Marc |date=2017-08-29 |title=Viewing distance requires large characters to ensure legibility on TV-set |url=https://doi.org/10.1145/3132129.3132133 |journal=Proceedings of the 29th Conference on l'Interaction Homme-Machine |series=IHM '17 |location=New York, NY, USA |publisher=Association for Computing Machinery |pages=147–155 |doi=10.1145/3132129.3132133 |isbn=978-1-4503-5109-6}}</ref>.
'''Please note!''' The optimal viewing distance is not suitable for [[user interface design|designing a user interface]]; It is the distance actually observed in households that should be used. It is much greater than the optimal viewing distance and highly variable<ref>{{Cite journal |last=Bertolus |first=Cédric |last2=Bailleul |first2=Daniel |last3=Mersiol |first3=Marc |date=2017-08-29 |title=Viewing distance requires large characters to ensure legibility on TV-set |url=https://doi.org/10.1145/3132129.3132133 |journal=Proceedings of the 29th Conference on l'Interaction Homme-Machine |series=IHM '17 |location=New York, NY, USA |publisher=Association for Computing Machinery |pages=147–155 |doi=10.1145/3132129.3132133 |isbn=978-1-4503-5109-6}}</ref>.

Revision as of 16:24, 12 April 2024

Optimal viewing distance

"The optimal viewing distance"[1] is based on the limits of the human eye, i.e. This is  its angle of resolution. Here, it concerns its ability to distinguish two pixels. For normal visual acuity (6/6 vision), this angle is 1 arcmin. To obtain a fixed distance for a given resolution, it must be expressed in picture heights (H)[1]. If a screen is 50 cm high and it is at a distance of 250 cm, then in picture heights, its distance is 5 H (250/50). Mathematically, this gives the distances shown in the following table:

A person on a couch watches the TV. Lines show that the distance between the couch and the TV corresponds to 3.2 times the picture heights.
Distance in picture heights. Here the distance is 3.2 picture heights (H). This is the optimal viewing distance for HD 1080 video.
Resolution Opti. Dist.
NTSC (640) × 480 7.2 H
PAL SECAM (720) × 576 6.0 H
HD 720 1280 × 720 4.8 H
HD 1080 1920 × 1080 3.2 H
4K UHD 3840 × 2160 1.6 H
8K UHD 7680 × 4320 0.8 H

This table can be used in a number of ways :

Find the optimal distance for a given screen. Example: for a 4K UHD screen 140 cm high (112 inches diagonal), the optimal distance is 140 × 1.6 = 224 cm.

Find the right screen size. Example: for a 1080 HDTV used at a distance of 250 cm, you need to find a screen whose height is close to 250/3.2 = 78 cm (63 inches diagonally).

Find the right video resolution. Example: a 53 cm high screen (43 inches diagonal), located at a distance of 300 cm, does not need to show video with a resolution higher than HD 720. Presenting a higher resolution means a larger ecological footprint with no perceptible gain.

Find the best seat in the cinema. DCI 4K cinema has the same number of lines as 4K UHD (the DCI 4K format is wider). The optimal distance is therefore 1.6 times the height of the screen. The best compromise with the ideal listening zone, the sweet spot, must be found; "Sound is 50 percent of the movie going experience" - George Lucas[2].

Please note! The optimal viewing distance is not suitable for designing a user interface; It is the distance actually observed in households that should be used. It is much greater than the optimal viewing distance and highly variable[3].

  1. ^ a b "Recommandation ITU-R BT.500-14, Methodologies for the subjective assessment of the quality of television images". www.itu.int. 2019. Retrieved 2024-04-11.
  2. ^ Fantel, Hans (May 3, 1992). "Home Entertainment; In the Action With 'Star Wars' Sound". The New York Times.
  3. ^ Bertolus, Cédric; Bailleul, Daniel; Mersiol, Marc (2017-08-29). "Viewing distance requires large characters to ensure legibility on TV-set". Proceedings of the 29th Conference on l'Interaction Homme-Machine. IHM '17. New York, NY, USA: Association for Computing Machinery: 147–155. doi:10.1145/3132129.3132133. ISBN 978-1-4503-5109-6.